You can not edit the Limit in CustomShopItems.ini
When you restart the server or a mapchange the plugin just gets the default value back!
The same happens If you try to edit trough cshop_edit
I'm using:
Custom Shop 4.2.4
CSHOP: Default Items 4.2.2
The same happens If you try to add a new line to CustomShopItems.ini, gets deleted